National Institute of Agricultural Biology, Huntingdon Road, Cambridge CB3 0LE, UK.
John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
J Exp Bot. 2017 Nov 28;68(20):5497-5509. doi: 10.1093/jxb/erx349.
Our previous genetic analysis of a tetraploid wild wheat species, Aegilops peregrina, predicted that a single gene per haploid genome, Bgc-1, controls B-type starch granule content in the grain. To test whether bread wheat (Triticum aestivum L.) has orthologous Bgc-1 loci, we screened a population of γ-irradiated bread wheat cv. Paragon for deletions of the group 4 chromosomes spanning Bgc-1. Suitable deletions, each encompassing ~600-700 genes, were discovered for chromosomes 4A and 4D. These two deletions are predicted to have 240 homoeologous genes in common. In contrast to single deletion mutant plants, double deletion mutants were found to lack B-type starch granules. The B-less grains had normal A-type starch granule morphology, normal overall starch content, and normal grain weight. In addition to variation in starch granule size distribution, the B-less wheat grains differed from controls in grain hardness, starch swelling power, and amylose content. We believe that these B-less wheat plants are the only Triticeae cereals available that combine substantial alterations in starch granule size distribution with minimal impact on starch content.
我们之前对四倍体野生小麦物种节节麦的遗传分析预测，每个单倍体基因组中的一个基因 Bgc-1 控制着籽粒中 B 型淀粉粒的含量。为了测试普通小麦（Triticum aestivum L.）是否具有同源的 Bgc-1 基因座，我们筛选了经γ射线辐照的普通小麦 Paragon 群体，以寻找跨越 Bgc-1 的第 4 组染色体缺失。发现了适合的缺失体，每个缺失体包含约 600-700 个基因，分别跨越 4A 和 4D 染色体。这两个缺失体预计有 240 个同源基因。与单个缺失突变体植物不同，双缺失突变体缺乏 B 型淀粉粒。缺乏 B 型淀粉粒的籽粒具有正常的 A 型淀粉粒形态、正常的总淀粉含量和正常的籽粒重量。除了淀粉粒大小分布的变化外，缺乏 B 型淀粉粒的小麦籽粒在籽粒硬度、淀粉膨胀力和直链淀粉含量方面与对照存在差异。我们认为这些缺乏 B 型淀粉粒的小麦植物是唯一的含有大量淀粉粒大小分布变化且对淀粉含量影响最小的禾本科谷物。
